val popupMenu: PopupMenu = PopupMenu(requireContext(), it)popupMenu.menu.add("测试Menu1")popupMenu.menu.add("测试Menu1")//反射获取Popupval mPopupMenu: Field = popupMenu.javaClass.getDeclaredField("mPopup")mPopupMenu.isAccessible = trueval mHelper: MenuPopupHelper = mPopupMenu.get(popupMenu) as MenuPopupHelperval standardMenuClass: Class<*> = Class.forName("androidx.appcompat.view.menu.StandardMenuPopup")//设置不测量Item宽度val mHasContentWidth: Field = standardMenuClass.getDeclaredField("mHasContentWidth")mHasContentWidth.isAccessible = truemHasContentWidth.setBoolean(mHelper.popup, true)//设置弹出宽度val mContentWidth: Field = standardMenuClass.getDeclaredField("mContentWidth")mContentWidth.setAccessible(true)//这里第二个参数填自己想要的宽度即可，获取屏幕宽度也行或者父控件mContentWidth.setInt(mHelper.popup, it.width)mHelper.show()
效果
参考了以下文章写出来的，感谢作者
https://www.jianshu.com/p/72f7c7d7dd1c
https://blog.csdn.net/xxdddail/article/details/90022666
